1. Field of the Invention
The present invention relates to a 2-pyridyl-4-thiazolidinone derivative and a pharmacologically acceptable salt thereof which exhibit remarkable antiulcer effect in experimental ulcer, especially stress-induced ulcer and are useful as medicines for treatment of gastric and duodenal ulcers of mammals including humans.
2. Description of the Prior Art
Hitherto, for treatment of gastric and duodenal ulcers, many medicines have been developed and used, for example:
(1) Gastric antacids and pepsin inhibitor which neutralize and inactive gastric juice.
(2) Anticholinergic agent and histamine H.sub.2 -receptor antagonist which inhibit secretion of gastric juice by antagonizing acetylcholine and histamine which are chemical transmitters of participating in gastric acid secretory mechanisms.
(3) Medicines which activate gastric muscosal defensive mechanisms and accelerate repair process of a damaged gastric mucosa.
Furthermore, recently the following medicines have been studies for development and application to anti-ulcer medicines and some of them have been put on the market.
(4) Medicines which utilize gastric acid inhibitory action or cytoprotective action of prostaglandins.
(5) Medicines which show anti-secretory action and anti-ulcer action owing to H.sup.+, K.sup.+ -ATPase inhibition (proton pump inhibitors).
However, there have not yet been developed anti-secretory and anti-ulcer medicines which act on central nervous system (CNS) and/or nervous system which transmits stimulus from CNS (hereinafter referred to as "Centrally acting inhibitory effect of gastric acid secretion or centrally acting gastric acid inhibitory effect").
These medicines having such effects are thought to be effective for treatment of recently increasing gastric and duodenal ulcers caused by stress.
The following seven reports have been made on study of 2-pyridylthiazolidine-4-one derivatives which are aimed at by the present invention.
That is, N-(substituted or unsubstituted phenyl and pyridyl) derivatives having uses as agricultural chemicals reported in Japanese Patent Kokai No. 54-145670; compounds including mainly N-(substituted or unsubstituted phenyl, benzyl and cycloalkyl) derivatives having uses as agricultural chemicals in Japanese Patent Kokai No. 55-55184; N-(carboxycyclohexylmethyl) derivatives having anticomplementary and N-(carboxymethylphenyl) derivatives having anti-inflammatory, analgesic and antirheumatic activity in Japanese Patent Kokai Nos. 57-85380 and 57-88170, respectively; N-(pyrazinyl) derivatives having uses as agricultural chemicals in Japanese Patent Kokai No. 58-183689; N-(substituted phenyl) derivatives having uses as intermediates in synthesis in U.S. Pat. No. 4,501,746; and N-(substituted carbamoyloxy) derivatives having a use as a cardiac in Japanese Patent Kokai No. 61-103881.
As mentioned above, not a few of 2-pyridylthiazolidin-4-one derivatives have excellent pharmacological action, but there has been made no report that they have any inhibitory effect of gastric acid secretion and anti-ulcer activity. Among the compounds having thiazolidin-4-one skeleton, Japanese Patent Kokai No. 57-64683 discloses that 2-substituted phenyl-5-alkylthiazolidin-4-one compounds have an effect as an antipeptic ulcer medicine.
However, none of these publications disclose that the compounds act on central nervous system and/or nervous system transmitting stimulus from central nervous system, resulting in remarkable central nervous type anti-secretory action and antiulcer action which are aimed at by the present invention.
As described hereinafter in Examples 2-(3,4-dimethoxyphenyl)-5-methylthiazolidin-4-one (Mezolidon) disclosed in the above Japanese Patent Kokai No. 57-64683 was evaluated by the test method employed in the present invention to find that this compound had extremely low effect as compared with the compound of the present invention and was nearly ineffective.
Medicines which are used for remedy of gastric and duodenal ulcers at present are roughly classified into (1) those which inhibit gastric acid secretion such as anticholinergic agent and H.sub.2 antagonist, (2) those which neutralize and inactive secreted digestive fluid such as antacid and pepsin inhibitor and (3) those which activate defensive function of gastric and duodenal muscosae against digestive fluid. These medicines all act at peripheral level where gastric acid is secreted or digestion is effected and exhibit curative effect of ulcer by direct affection on the function of alimentary tract.
However, the functions of gastric secretion, gastro-duodenal motility and mucosal blood flow are all controlled by brain and it is considered that irregularity in the regulation by brain due to stress or the like will cause ulceration. That is, emission of abnormal stimulus from brain due to stress or the like induces acceleration of gastric acid secretion or gastric motility through excitation of vagus nerve and reduction of mucosal blood flow through excitation of splanchnic nerve, resulting in self digestion of gastric walls.
In other words, as causes of peptic ulcer, not only part of the peripheral nervous system, but also that of the central nervous system are important. Especially, for humans, mental and physical stress is considered to give a great effect on occurrence, retention and recurrence of ulcer and ulcer is considered to be one of psychological diseases. Therefore, if irregularity of central regulation for alimentary tract functions such as gastric acid secretion which has been caused by stress can be improved, this is expected to be an effective therapy of ulcer.
However, there have been substantially no medicines which act on central nervous system or nervous system which transmits stimulus from central nervous system to exhibit anti-secretory effect and anticulcer effect. Therefore, in actual treatment of ulcer, mostly ordinary anticulcer medicine is used in combination with antianxiety medicine, tranquillizer or the like. However, these medicines are not selective for central regulatory mechanisms of gastric acid secretion and have depressive effect on central nervous system, so they often cause side-effects such as drowsiness and hypoactivity.